This invention relates generally to the field of tackle used for securing ropes and cables in operative position on rigging devices and the like, and more particularly to an improved device for locking a shackle in closed condition by preventing the selectively removable pin from becoming accidentally dislodged.
The classic shackle for this purpose consists of a generally U-shaped member, the free ends of which are provided with coaxially aligned bores accommodating an elongated pin which threadedly engages at least one of the bores and spans the open area between the free ends. In some cases, the pin is provided with a transversely extending bore which accommodates a cotter pin which penetrates the shackle pin to prevent more than a limited degree of movement between the pin and the shackle body. While not without utility, cotter pins are subject to breakage under stress, and, further, they normally require a tool to spread the legs of the pin during engagement, as well as some sort of clamping device to straighten the legs prior to removal.
Safety guards for bolts and the like, are also known in the art. The U.S. Pat. No. 1,303,293 granted to W. Gries describes a safety guard for a bolt affixed in such manner as to not be readily removable. The U.S. Pat. No. 1,550,784 to G. T. Cooke discloses an L-shaped locking menber of sheet metal which is folded about a pin or bolt to be retained. However, such a locking device is for non-repeated use only.